The accretion-induced collapse (AIC) of a white dwarf may lead to the formation of a protoneutron star and a collapse-driven supernova explosion. This process represents a path alternative to thermonuclear disruption of accreting white dwarfs in type Ia supernovae. In the AIC scenario, the supernova explosion energy is expected to be small and the resulting transient short-lived, making it hard to detect by electromagnetic means alone. Neutrino and gravitational-wave (GW) observations may provide crucial information necessary to reveal a potential AIC. Motivated by the need for systematic predictions of the GW signature of AIC, we present results from an extensive set of general-relativistic AIC simulations using a microphysical finite-temperature equation of state and an approximate treatment of deleptonization during collapse. Investigating a set of 114 progenitor models in axisymmetric rotational equilibrium, with a wide range of rotational configurations, temperatures and central densities, and resulting white dwarf masses, we extend previous Newtonian studies and find that the GW signal has a generic shape akin to what is known as a “type III” signal in the literature. Despite this reduction to a single type of waveform, we show that the emitted GWs carry information that can be used to constrain the progenitor and the postbounce rotation. We discuss the detectability of the emitted GWs, showing that the signal-to-noise ratio for current or next-generation interferometer detectors could be high enough to detect such events in our Galaxy. Furthermore, we contrast the GW signals of AIC and rotating massive star iron core collapse and find that they can be distinguished, but only if the distance to the source is known and a detailed reconstruction of the GW time series from detector data is possible. Some of our AIC models form massive quasi-Keplerian accretion disks after bounce. The disk mass is very sensitive to progenitor mass and angular momentum distribution. In rapidly differentially rotating models whose precollapse masses are significantly larger than the Chandrasekhar mass, the resulting disk mass can be as large as $\sim 0.8M_{\odot }$. Slowly and/or uniformly rotating models that are limited to masses near the Chandrasekhar mass produce much smaller disks or no disk at all. Finally, we find that the postbounce cores of rapidly spinning white dwarfs can reach sufficiently rapid rotation to develop a gravitorotational bar-mode instability. Moreover, many of our models exhibit sufficiently rapid and differential rotation to become subject to recently discovered low-$E_{\mathrm{rot}}/|W|$-type dynamical instabilities.

We explore unification of dark matter and dark energy in a theory containing a scalar field of non-Lagrangian type, obtained by direct insertion of a kinetic term into the energy-momentum tensor. This scalar is different from quintessence, having an equation of state between $-1$ and 0 and a zero sound speed in its rest frame. We solve the equations of motion for an exponential potential via a rewriting as an autonomous system, and demonstrate the observational viability of the scenario, for sufficiently small exponential potential parameter $\lambda$, by comparison to a compilation of kinematical cosmological data.

We propose counting peaks in weak lensing (WL) maps, as a function of their height, to probe models of dark energy and to constrain cosmological parameters. Because peaks can be identified in two-dimensional WL maps directly, they can provide constraints that are free from potential selection effects and biases involved in identifying and determining the masses of galaxy clusters. As a pilot study, we have run cosmological N-body simulations to produce WL convergence maps in three models with different constant values of the dark energy equation-of-state parameter, $w=-0.8$, $-1$, and $-1.2$, with a fixed normalization of the primordial power spectrum (corresponding to present-day normalizations of ${\sigma }_8=0.742$, 0.798, and 0.839, respectively). By comparing the number of WL peaks in eight convergence bins in the range of $-0.1<\kappa <0.4$, in multiple realizations of a single simulated $3\times 3$ degree field, we show that the first (last) pair of models differ at the 95% (85%) confidence level. A survey with depth and area comparable to those expected from the Large Synoptic Survey Telescope should have a factor of $\approx 50$ better parameter sensitivity. These results warrant further investigation, in order to assess the constraints available when marginalization over other uncertain parameters is included, and with the specifications of a realistic survey folded into the analysis. Here we find that relatively low-amplitude peaks ($\kappa \sim 0.03$), which typically do not correspond to a single collapsed halo along the line of sight, account for most of the parameter sensitivity. We study a range of smoothing scales and source galaxy redshifts ($z_s$). With a fixed source galaxy density of $15{\mathrm{arcmin}}^{-2}$, the best results are provided by the smallest scale we can reliably simulate, 1 arcmin, and $z_s=2$ provides substantially better sensitivity than $z_s\le 1.5$.

We report the constraints on the dark energy equation-of-state $w(z)$ using the latest “Constitution” SNe sample combined with the WMAP5 and Sloan Digital Sky Survey data. Assuming a flat Universe, and utilizing the localized principal component analysis and the model selection criteria, we find that the $\Lambda \mathrm{CDM}$ model is generally consistent with the current data, yet there exists a weak hint of the possible dynamics of dark energy. In particular, a model predicting $w(z)<-1$ at $z\in [0.25,0.5)$ and $w(z)>-1$ at $z\in [0.5,0.75)$, which means that $w(z)$ crosses $-1$ in the range of $z\in [0.25,0.75)$, is mildly favored at 95% confidence level. Given the best fit model for current data as a fiducial model, we make future forecast from the joint data sets of Joint Dark Energy Mission, Planck, and Large Synoptic Survey Telescope, and we find that the future surveys can reduce the error bars on the $w$ bins by roughly a factor of 10 for a 5-$w$-bin model.

A nearby core collapse supernova will produce a burst of neutrinos in several detectors worldwide. With reasonably high probability, the Earth will shadow the neutrino flux in one or more detectors. In such a case, for allowed oscillation parameter scenarios, the observed neutrino energy spectrum will bear the signature of oscillations in Earth matter. Because the frequency of the oscillations in energy depends on the path length traveled by the neutrinos in the Earth, an observed spectrum also contains information about the direction to the supernova. We explore here the possibility of constraining the supernova location using matter oscillation patterns observed in a detector. Good energy resolution (typical of scintillator detectors), well-known oscillation parameters, and optimistically large (but conceivable) statistics are required. Pointing by this method can be significantly improved using multiple detectors located around the globe. Although it is not competitive with neutrino-electron elastic scattering-based pointing with water Cherenkov detectors, the technique could still be useful.

It has been suggested recently to study the dynamics of a gravitating gluon condensate $q$ in the context of a spatially flat Friedmann-Robertson-Walker universe. The expansion of the Universe (or, more generally, the presence of a nonvanishing Ricci curvature scalar $R$) perturbs the gluon condensate and may induce a nonanalytic term $\tilde{h}(R,q)$ in the effective gravitational action. The aim of this article is to explore the cosmological implications of a particular nonanalytic term $\tilde{h}\propto \eta |R{|}^{1/2}|q{|}^{3/4}$. With a quadratic approximation of the gravitating gluon-condensate vacuum energy density ${\rho }_V(q)$ near the equilibrium value $q_0$ and a small coupling constant $\eta$ of the modified-gravity term $\tilde{h}$, an “accelerating universe” is obtained which resembles the present Universe, both qualitatively and quantitatively. The unknown component $X$ of this model universe (here, primarily due to modified-gravity effects) has an effective equation-of-state parameter ${\overline{w}}_X$ which is found to evolve toward the value $-1$ from above.

Phase diagram of a chiral random matrix model with the two degenerate quarks (u and d) and the s-quark at finite temperature and density is presented. The model exhibits a first-order transition at finite temperature for three massless flavors, owing to the ${\mathrm{U}}_A(1)$ breaking determinant term. We study the order of the transition with changing the quark masses and the quark chemical potential, and show that the first-order transition region expands as the chemical potential increases. We also discuss the behavior of the meson masses and the susceptibilities near the critical point.

In this note, we calculate the branching ratio of $B_c\to J/\psi K$ in the framework of perturbative QCD approach based on $k_T$ factorization. This decay can occur only via tree level diagrams in the standard model. We find that the branching ratio of $B_c\to J/\psi K$ is about $(1-3)\times {10}^{-4}$. The large branching ratio and the clear signals of the final states make the measurement of $B_c\to J/\psi K$ easily at LHC-b experiments.

We study the possibility that the three mass states of the ordinary active neutrinos actually split into pairs of quasidegenerate states, with $\Delta m_{k{k}^{\prime }}^2\sim {10}^{-12}{\mathrm{eV}}^2$ or less, as a result of mixing of active neutrinos with sterile neutrinos. While in laboratory experiments these quasidegenerate pairs will look identical to single active states, the $CP$ phase factors associated with active-sterile mixing might cause cancellations in the effective electron neutrino mass $m_{ee}$ measured in the neutrinoless double beta decay experiments thereby revealing the split nature of states.

We propose a Randall-Sundrum model with a bulk family symmetry based on the double tetrahedral group, $T^{\prime }$, which generates the tribimaximal neutrino mixing pattern and a realistic CKM matrix, including $CP$ violation. Unlike 4D models where the generation of mass hierarchy requires additional symmetry, the warped geometry naturally gives rise to the fermion mass hierarchy through wave function localization. The $T^{\prime }$ symmetry forbids tree-level flavor-changing-neutral-currents in both the quark and lepton sectors, as different generations of fermions are unified into multiplets of $T^{\prime }$. This results in a low first KK mass scale and thus the model can be tested at collider experiments.

We propose measurements of the deeply virtual Compton amplitude (DVCS) ${\gamma }^{*}\to h\overline{h}\gamma$ in the timelike $t=(p_h+p_{\overline{h}}{)}^2>0$ kinematic domain which is accessible at electron-positron colliders via the radiative annihilation process $e^{+}{e}^{-}\to h\overline{h}\gamma$. These processes allow the measurement of timelike deeply virtual Compton scattering for a variety of $h\overline{h}$ hadron pairs such as ${\pi }^{+}{\pi }^{-}$, $K^{+}{K}^{-}$, and $D\overline{D}$ as well as $p\overline{p}$. As in the conventional spacelike DVCS, there are interfering coherent amplitudes contributing to the timelike processes involving $C=-$ form factors. The interference between the amplitudes measures the phase of the $C=+$ timelike DVCS amplitude relative to the phase of the timelike form factors and can be isolated by considering the forward-backward $e^{+}\leftrightarrow e^{-}$ asymmetry. The $J=0$ fixed pole contribution which arises from the local coupling of the two photons to the quark current plays a special role. As an example we present a simple model.

We present three measurements of the top-quark mass in the lepton plus jets channel with approximately $1.9{\mathrm{fb}}^{-1}$ of integrated luminosity collected with the CDF II detector using quantities with minimal dependence on the jet energy scale. One measurement exploits the transverse decay length of $b$-tagged jets to determine a top-quark mass of ${166.9}_{-8.5}^{+9.5}(\mathrm{stat})\pm 2.9(\mathrm{syst})\mathrm{GeV}/c^2$, and another the transverse momentum of electrons and muons from $W$-boson decays to determine a top-quark mass of ${173.5}_{-8.9}^{+8.8}(\mathrm{stat})\pm 3.8(\mathrm{syst})\mathrm{GeV}/c^2$. These quantities are combined in a third, simultaneous mass measurement to determine a top-quark mass of $170.7\pm 6.3(\mathrm{stat})\pm 2.6(\mathrm{syst})\mathrm{GeV}/c^2$.

Based on our idea of an alternative supersymmetrization of the Nambu–Jona-Lasinio model for dynamical symmetry breaking, we analyze the resulting new model with a holomorphic dimension-five operator in the superpotential. The approach provides a new direction for modeling dynamical symmetry breaking in a supersymmetric setting. In particular, we adopt the idea to formulate a model that gives rise to the minimal supersymmetric standard model as the low energy effective theory with both Higgs superfields as composites. A renormalization group analysis is performed to establish the phenomenological viability of the scenario, with admissible background scale that could go down to the TeV scale. We give the Higgs mass range predicted.

We use gauge/gravity duality to study the thermodynamics of a field theory with asymptotic freedom in the ultraviolet and a fixed point in the infrared. We find a high temperature quark-gluon phase and a low $T$ conformal unparticle phase. The phase transition between the phases is of first order or continuous, depending on the ratio of the radii of asymptotic anti–de Sitter spaces at $T=0$ and $T=\infty$. This is a prediction from a model of gauge/gravity duality, not yet verified on the field theory side.

We investigate the dissociation of a heavy meson in the medium composed of light quarks and gluons. In the quark-gluon plasma, the dissociation length of the heavy meson becomes short as the temperature or quark chemical potential increases. On the contrary, in the hadronic phase the dissociation length becomes large as the chemical potential increases, due to the different dissociation mechanism with one used in the quark-gluon plasma.

We construct models of self-interacting scalar fields whose Bogomol’nyi-Prasad-Sommerfeld solutions exhibit kink profiles which can be continuously deformed into two kinks by varying one of the parameters of the self-interacting potential. The effective models are obtained from other models with two interacting scalar fields. The effective models are then applied in a brane-world scenario where we analyze the consequences of the thicker branes in the warped geometry and in the localization of gravity.

We discuss the initial-boundary value problem for the Baumgarte-Shapiro-Shibata-Nakamura evolution system of Einstein’s field equations which has been used extensively in numerical simulations of binary black holes and neutron stars. We specify nine boundary conditions for this system with the following properties: (i) they impose the momentum constraint at the boundary, which is shown to preserve all the constraints throughout evolution; (ii) they approximately control the incoming gravitational degrees of freedom by specifying the Weyl scalar ${\Psi }_0$ at the boundary; (iii) they control the gauge freedom by requiring a Neumann boundary condition for the lapse, by setting the normal component of the shift to zero, and by imposing a Sommerfeld-like condition on the tangential components of the shift; and (iv) they are shown to yield a well-posed problem in the limit of weak gravity. Possible numerical applications of our results are also discussed briefly.

Primordial magnetic fields and massive neutrinos can leave an interesting signal in the CMB temperature and polarization. We perform a systematic analysis of general perturbations in the radiation-dominated universe, accounting for any primordial magnetic field and including leading-order effects of the neutrino mass. We show that massive neutrinos qualitatively change the large-scale perturbations sourced by magnetic fields, but that the effect is much smaller than previously claimed. We calculate the CMB power spectra sourced by inhomogeneous primordial magnetic fields, from before and after neutrino decoupling, including scalar, vector and tensor modes, and consistently modeling the correlation between the density and anisotropic stress sources. In an appendix we present general series solutions for the possible regular primordial perturbations.

Compact stars made of quark matter, rather than confined hadronic matter, are expected to form a color superconductor. This superconductor ought to be threaded with rotational-vortex lines, within which the star’s interior magnetic field is at least partially confined. The vortices (and thus magnetic flux) would be expelled from the star during stellar spin-down, leading to magnetic reconnection at the surface of the star and the prolific production of thermal energy. In this paper, we show that this energy release can reheat quark stars to exceptionally high temperatures, such as observed for soft gamma repeaters, anomalous x-ray pulsars, and x-ray dim isolated neutron stars. Moreover, our numerical investigations of the temperature evolution, spin-down rate, and magnetic field behavior of such superconducting quark stars suggest that soft gamma repeaters, anomalous x-ray pulsars, and x-ray dim isolated neutron stars may be linked ancestrally. Finally, we discuss the possibility of a time delay before the star enters the color-superconducting phase, which can be used to estimate the density at which quarks deconfine. From observations, we find this density to be of the order of 5 times that of nuclear saturation.

Fermion mass generation for the third generation is considered within a unified Higgs model with a single pair of vector-spinor $144+\overline{144}$ of Higgs multiplets. Extending a previous work it is shown that much larger masses can arise for all the third generation fermions from mixing with 45 and 120 matter multiplets via the cubic couplings $16·45·\overline{144}$ and $16·120·144$ in addition to the quartic couplings. Further, it is found that values of $\tan \beta$ as low as 10 can allow for a $b-\tau -t$ unification consistent with the current data. The quartic and cubic couplings naturally lead to Dirac as well as Majorana neutrino masses necessary for the generation of a seesaw neutrino mass of the right size for the tau neutrino.